backends: add set_initial_registers_tid callback for RISC-V

This fixes the backtrace-dwarf and deleted tests, and lets
backtrace-native run a bit further.

Signed-off-by: Andreas Schwab <[email protected]>

backends/ChangeLog

@@ -1,3 +1,9 @@
+2018-07-11  Andreas Schwab  <[email protected]>
+
+	* Makefile.am (riscv_SRCS): Add riscv_initreg.c.
+	* riscv_initreg.c: New file.
+	* riscv_init.c (riscv_init): Hook set_initial_registers_tid.
+
 2018-06-16  Yonghong Song  <[email protected]>
 
 	* Makefile.am (bpf_SRCS): Add bpf_symbol.c.

backends/Makefile.am

@@ -131,7 +131,8 @@ cpu_bpf = ../libcpu/libcpu_bpf.a
 libebl_bpf_pic_a_SOURCES = $(bpf_SRCS)
 am_libebl_bpf_pic_a_OBJECTS = $(bpf_SRCS:.c=.os)
 
-riscv_SRCS = riscv_init.c riscv_symbol.c riscv_cfi.c riscv_regs.c
+riscv_SRCS = riscv_init.c riscv_symbol.c riscv_cfi.c riscv_regs.c \
+	     riscv_initreg.c
 libebl_riscv_pic_a_SOURCES = $(riscv_SRCS)
 am_libebl_riscv_pic_a_OBJECTS = $(riscv_SRCS:.c=.os)
 

backends/riscv_init.c

@@ -57,6 +57,7 @@ riscv_init (Elf *elf __attribute__ ((unused)),
   eh->frame_nregs = 66;
   HOOK (eh, check_special_symbol);
   HOOK (eh, machine_flag_check);
+  HOOK (eh, set_initial_registers_tid);
 
   return MODVERSION;
 }

backends/riscv_initreg.c

@@ -0,0 +1,77 @@
+/* Fetch live process registers from TID.
+   This file is part of elfutils.
+
+   This file is free software; you can redistribute it and/or modify
+   it under the terms of either
+
+     * the GNU Lesser General Public License as published by the Free
+       Software Foundation; either version 3 of the License, or (at
+       your option) any later version
+
+   or
+
+     * the GNU General Public License as published by the Free
+       Software Foundation; either version 2 of the License, or (at
+       your option) any later version
+
+   or both in parallel, as here.
+
+   elfutils is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received copies of the GNU General Public License and
+   the GNU Lesser General Public License along with this program.  If
+   not, see <http://www.gnu.org/licenses/>.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "system.h"
+#include <assert.h>
+#if defined __riscv && defined __linux__
+# include <sys/uio.h>
+# include <sys/procfs.h>
+# include <sys/ptrace.h>
+#endif
+
+#define BACKEND riscv_
+#include "libebl_CPU.h"
+
+bool
+riscv_set_initial_registers_tid (pid_t tid __attribute__ ((unused)),
+				 ebl_tid_registers_t *setfunc __attribute__ ((unused)),
+				 void *arg __attribute__ ((unused)))
+{
+#if !defined __riscv || !defined __linux__
+  return false;
+#else /* __riscv */
+
+  /* General registers.  */
+  elf_gregset_t gregs;
+  struct iovec iovec;
+  iovec.iov_base = &gregs;
+  iovec.iov_len = sizeof (gregs);
+  if (ptrace (PTRACE_GETREGSET, tid, NT_PRSTATUS, &iovec) != 0)
+    return false;
+
+  /* X0 is constant 0.  */
+  Dwarf_Word zero = 0;
+  if (! setfunc (0, 1, &zero, arg))
+    return false;
+
+  /* X1..X31.  */
+  if (! setfunc (1, 32, (Dwarf_Word *) &gregs[1], arg))
+    return false;
+
+  /* PC.  */
+  if (! setfunc (-1, 1, (Dwarf_Word *) &gregs[0], arg))
+    return false;
+
+  /* FP registers not yet supported.  */
+
+  return true;
+#endif /* __riscv */
+}